The present invention generally relates to transferring systems useful in processing applications and, more particularly, to a transferring system for use in a processing apparatus having a plurality of processing stations for sequentially processing a plurality of articles as the articles are moved from station to station through the plurality of processing stations.
Transfer systems for transferring articles through a plurality of processing stations have long been utilized in practice in the prior art. For example, U.S. Pat. No. 3,658,197 describes a transferring system including a horizontal beam having a plurality of transferring units connected thereto for moving articles through a plurality of processing stations. The beam is moved vertically by a plurality of lifting units to lift the articles from the processing stations. The beam is further moved horizontially by way of a hydraulic piston-cylinder unit to move the articles to the next processing station. This system is problematic, however, since each transferring unit is confined to movement with the horizontal beam and thus can not move parts continuously along an endless path. Further, since the articles do not always remain attached to the transferring units while being processed in the stations, there is a risk that a transferring unit or an article will become misaligned resulting in an article not being picked up and properly transferred.
U.S. Pat. No. 2,997,191 describes a transferring system including a plurality of work carriers which move independently of one another to transfer workpieces through a plurality of processing stations. The work carriers are moved horizontally on rail sections by a plurality of pusher members located on two separate conveyor devices. The work carriers are also moved vertically to lift workpieces out of the processing stations by way of vertically movable rail sections. This system is disadvantageous since it requires more than one conveyor device having pusher members thereon in order to transfer the work carriers. Further, since the work carriers do not remain attached to a conveyor device, there is a risk that a pusher member on a conveyor device or a work carrier will become misaligned resulting in a workpiece not being properly transferred.
A further transferring system is known which is similar to the one described above in U.S. Pat. No. 2,997,191. This transferring system includes a plurality of work carriers which move independently of one another along rail sections to transfer workpieces through a plurality of processing stations. The work carriers are moved vertically to lift the workpieces out of the processing stations by vertically movable rail sections which are displaced by hydraulic actuators. The system is disadvantageous because it requires hydraulic actuators, which are expensive to install and problematic to maintain.
U.S. Pat. No. 4,377,986 discloses a transferring system, including a vertically reciprocating single-beam hoist having a plurality of transferring carts located thereon, for moving workpieces through a number of processing stations. The transferring carts are reciprocated horizontally along the hoist in order to transfer the workpieces between the processing stations. Since the transferring carts are confined to horizontal movement along the beam, the carts are not able to move workpieces continuously along an endless path. Further, since the workpieces do not always remain attached to the transferring carts while being processed in the stations, there is a risk that a cart or a workpiece will become misaligned resulting in a workpiece not being picked up and properly transferred.
U.S. Pat. No. 3,684,080 discloses a trolley conveyor system for use while unloading fowl, such as turkeys, from trucks. The system includes an endless cable having a plurality of trolleys connected thereto which move about an endless path on a track system. A portion of the trolley conveyor system is vertically displaceable in order to permit an operator to conveniently reach the birds at various levels on the bed of the truck. The conveyor system is capable of adjusting the overall length of the track system in order to compensate for the changes brought about by raising and lowering the displaced portion. This system is not useful in processing applications, however, since it is not employed with a processing apparatus having a plurality of processing stations for sequentially processing a plurality of articles.
Accordingly, a need exists for an alternative transferring system for transferring a plurality of articles through a plurality of processing stations. An approach is desired in which a transferring system includes a series of work carriers connected to an endless conveyor traveling through an endless path with a portion of the endless conveyor capable of being displaced vertically in order to transfer a plurality of workpieces into and out of a plurality of processing stations.